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Introduction to Metabolism

Introduction to Metabolism. How the Universe Really Works. What is Energy?. Capacity to do work Forms of energy Electrical Mechanical Chemical Light Heat. What is Energy?. Capacity to do work Forms of energy Potential energy Kinetic energy. Kinetic and potential energy: dam.

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Introduction to Metabolism

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  1. Introduction to Metabolism How the Universe Really Works

  2. What is Energy? • Capacity to do work • Forms of energy • Electrical • Mechanical • Chemical • Light • Heat

  3. What is Energy? • Capacity to do work • Forms of energy • Potential energy • Kinetic energy

  4. Kinetic and potential energy: dam • Stored Water = Potential Energy • Moving Water = Kinetic Energy

  5. Kinetic and potential energy: cheetah at rest and running • Cheetah resting = Cheetah running = Potential Energy Kinetic Energy

  6. Energy can be converted from one form to another. • As the boy climbs the ladder to the top of the slide he is converting his kinetic energy to potential energy. • As he slides down, the potential energy is converted back to kinetic energy. • It was the potential energy in the food he had eaten earlier that provided the energy that permitted him to climb up initially. Fig. 6.2

  7. One-Way Flow of Energy • The sun is life’s primary energy source • Producers trap energy from the sun and convert it into chemical bond energy • Allorganisms use the energy stored in the bonds of organic compounds to do work

  8. What Can Cells Do with Energy? • Energy inputs become coupled to energy-requiring processes • Cells use energy for: • Chemical work • Mechanical work • Electrochemical work

  9. Energy Relationships large energy-rich molecules (fats, complex carbohydrates, proteins, nucleic acids) ADP + Pi BIOSYNTHETIC PATHWAYS (ANABOLIC) DEGRADATIVE PATHWAYS (CATABOLIC) simple organic compounds simple sugars, amino acids, fatty acids, nucleotides ATP energy-poor products such as carbon dioxide, water ENERGY INPUT

  10. Thermodynamics • Thermodynamics is the study of energy transformations. • system indicates the matter under study and the surroundings are everything • closed systemis isolated from its surroundings. • In an open system energy (and often matter) can be transferred between the system and surroundings. • Organisms are open systems. • They absorb energy - light or chemical energy in organic molecules - and release heat and metabolic waste products

  11. First Law of Thermodynamics • The total amount of energy in the universe remains constant • Energy can undergo conversions from one form to another, but it cannot be created or destroyed

  12. Second Law of Thermodynamics • No energy conversion is ever 100 percent efficient • The total amount of energy is flowing from high-energy forms to forms lower in energy

  13.  Two laws of thermodynamics • Conversion of energy from chemical potential to kinetic mechanical energy. • Some energy is lost to heat.

  14. Entropy • Measure of degree of disorder in a system • The world of life can resist the flow toward maximum entropy only because it is resupplied with energy from the sun

  15. Free Energy • Free energy can be thought of as a measure of the stability of a system. • Systems that are high in free energy - compressed springs, separated charges - are unstable and tend to move toward a more stable state - one with less free energy. • Systems that tend to change spontaneously are those that have high energy, low entropy, or both. • In any spontaneous process, the free energy of a system decreases.

  16.   Energy changes in exergonic and endergonic reactions

  17. The Math • We can represent this change in free energy from the start of a process until its finish by: • delta G = G final state - G starting state • Or delta G = delta H - T delta S • For a system to be spontaneous, the system must either give up energy (decrease in H), give up order (decrease in S), or both. • Delta G must be negative. • The greater the decrease in free energy, the greater the maximum amount of work that a spontaneous process can perform. • Nature runs “downhill”.

  18. Still Calculating • The magnitude of delta G for an exergonic reaction is the maximum amount of work the reaction can perform. • For the overall reaction of cellular respiration: • C6H12O6 + 6O2 -> 6CO2 + 6H2O • delta G = -686 kcal/mol • Through this reaction 686 kcal have been made available to do work in the cell. • The products have 686 kcal less energy than the reactants

  19. Endergonic Reactions • Energy input required • Product has more energy than starting substances product with more energy (plus by-products 602 and 6H2O) ENERGY IN 6 12

  20. Exergonic Reactions • Energy is released • Products have less energy than starting substance energy-rich starting substance ENERGY OUT + 602 6 6 products with less energy

  21. Energy Carriers Enzymes Cofactors Participants in Metabolic Pathways • Substrates • Intermediates • End products

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